Study on Methods for Removal and Concentration of Metal Ions Solved in Water Using Macro-Molecules

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1. Water-soluble chelating polymers, poly(α-acethylaminoacrylic acid) (abbreviation : P4A) and poly(N-methacryloyl-L-alanine) (abbreviation : PMLA) were prepared. The weight average molecular weight of P4A and PMLA were 1100000 and 2200000, respectively. Binding equilibria of P4A and PMLA with divalent metal ions (Co(II), Ni(II), Cu(II), Zn(II), Pb(II)) were measured by a batch ultrafiltration method in the pH range 4-6. It was shown that the binding equilibrium curves were reasonably well represented by the complexation model proposed previously. The equilibrium and successive stability constants were determined by fitting the binding curves calculated from the model to the experimental ones at every solution pH.2. Microcapsules .containing 2-ethylhexyl 2-ethylhexyl. Phosphonate(PC88A) were prepared by an insitu polymerization of divinyl benzene with water-oil-water emulsion. Almost all the microcapsules prepared were spherical with diameters of 200-300 μm (SEM observation). Adsorption equilibria of rare earth metal ions were measured in the pH range 1-4. It was shown that the microcapsules adsorbed rare earth metal ions even in acidic solution of pH 2-3. From these results, the microcapsules seem to be useful to recover or concentration metal ions dissolved in water.3. Immobilization of metal ions dissolved in water was examined with calcium phosphate, calcium hydrogen phosphate and calcium dihydrogen phosphate. Lead ions were favorably removed with these three kinds of phosphates, but Co(II), Cu(II) and Cd(II) were removed with only calcium hydrogen phosphate. The immobilization of metal ions with phosphates was discussed based on a dissolution-precipitation mechanism.